Consolidated Statements of Cash Flows - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Operating Activities
Net income		$ 16,939	$ 181,598
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		235,381	619,715
Equity in net income from unconsolidated joint ventures		(10,026)	(15,937)
Distributions of cumulative earnings from unconsolidated joint ventures		12,388	15,260
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate		(15,136)	(43,363)
Depreciable real estate reserves		85,336	10,387
Loss (gain) on sale of real estate, net		3,256	(210,353)
(Gain) loss on sale of investments in marketable securities		(3,262)	83
Deferred rents receivable		(23,237)	53,042
Other non-cash adjustments	[1]	17,551	(164,276)
Changes in operating assets and liabilities:
Restricted cash—operations		5,023	(10,069)
Tenant and other receivables		1,447	4,820
Related party receivables		(7,869)	(2,386)
Deferred lease costs		(23,560)	(31,951)
Other assets		680	4,362
Accounts payable, accrued expenses, other liabilities and security deposits		(10,660)	(33,635)
Deferred revenue and land leases payable		29,471	(3,919)
Net cash provided by operating activities		313,722	373,378
Investing Activities
Acquisitions of real estate property		(19)	(37,728)
Additions to land, buildings and improvements		(165,262)	(157,118)
Escrowed cash—capital improvements/acquisition deposits/deferred purchase price		11,980	76,220
Investments in unconsolidated joint ventures		(93,182)	(25,389)
Distributions in excess of cumulative earnings from unconsolidated joint ventures		93,688	161,413
Net proceeds from disposition of real estate/joint venture interest		23,082	1,916,312
Proceeds from sale or redemption of marketable securities		54,363	5,180
Purchases of marketable securities		0	(331)
Other investments		3,014	(2,987)
Origination of debt and preferred equity investments		(854,577)	(227,196)
Repayments or redemption of debt and preferred equity investments		663,140	418,371
Net cash (used in) provided by investing activities		(263,773)	2,126,747
Financing Activities
Proceeds from mortgages and other loans payable		779,642	250,514
Repayments of mortgages and other loans payable		(693,243)	(1,663,616)
Proceeds from revolving credit facility and senior unsecured notes		1,072,800	700,000
Repayments of revolving credit facility and senior unsecured notes		(875,697)	(1,664,296)
Proceeds from stock options exercised and DRIP issuance		11,706	4,431
Repurchase of common stock		(211,599)	0
Redemption of preferred stock		(125)	(2,849)
Distributions to noncontrolling interests in other partnerships		(609)	(9,866)
Contributions from noncontrolling interests in other partnerships		33,009	1,434
Distributions to noncontrolling interests in the Operating Partnership		(7,112)	(6,009)
Dividends/Distributions paid on common and preferred stock/units		(168,678)	(156,234)
Other obligations related to loan participations		10,000	76,500
Deferred loan costs and capitalized lease obligation		(8,521)	(9,307)
Net cash used in financing activities		(58,427)	(2,479,298)
Net (decrease) increase in cash and cash equivalents		(8,478)	20,827
Cash and cash equivalents at beginning of year		279,443	255,399
Cash and cash equivalents at end of period		270,965	276,226
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of units in the Operating Partnership		20,824	51,647
Redemption of units in the Operating Partnership for stock		13,242	11,795
Derivative instruments at fair value		6,766	7,701
Exchange of debt investment for equity in joint venture		0	68,581
Issuance of preferred units relating to a real estate acquisition		0	22,793
Tenant improvements and capital expenditures payable		7,210	11,637
Fair value adjustment to noncontrolling interest in Operating Partnership		12,712	906
Deconsolidation of subsidiaries		328,644	0
Transfer of assets related to assets held for sale		173,918	1,931,217
Transfer of liabilities related to assets held for sale		149	1,612,008
Deferred leasing payable		800	1,222
Transfer of assets related to assets held for sale		5,754	13,471
Share repurchase payable		41,598	0
Bond repurchase payable		65,416	0
Proceeds from sale held in restricted cash		38,166	0
SL Green Operating Partnership
Operating Activities
Net income		16,939	181,598
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		235,381	619,715
Equity in net income from unconsolidated joint ventures		(10,026)	(15,937)
Distributions of cumulative earnings from unconsolidated joint ventures		12,388	15,260
Equity in net gain on sale of interest in unconsolidated joint venture interest/real estate		(15,136)	(43,363)
Depreciable real estate reserves		85,336	10,387
Loss (gain) on sale of real estate, net		3,256	(210,353)
(Gain) loss on sale of investments in marketable securities		(3,262)	83
Deferred rents receivable		(23,237)	53,042
Other non-cash adjustments		17,551	(164,276)
Changes in operating assets and liabilities:
Restricted cash—operations		5,023	(10,069)
Tenant and other receivables		1,447	4,820
Related party receivables		(7,869)	(2,386)
Deferred lease costs		(23,560)	(31,951)
Other assets		680	4,362
Accounts payable, accrued expenses, other liabilities and security deposits		(10,660)	(33,635)
Deferred revenue and land leases payable		29,471	(3,919)
Net cash provided by operating activities		313,722	373,378
Investing Activities
Acquisitions of real estate property		(19)	(37,728)
Additions to land, buildings and improvements		(165,262)	(157,118)
Escrowed cash—capital improvements/acquisition deposits/deferred purchase price		11,980	76,220
Investments in unconsolidated joint ventures		(93,182)	(25,389)
Distributions in excess of cumulative earnings from unconsolidated joint ventures		93,688	161,413
Net proceeds from disposition of real estate/joint venture interest		23,082	1,916,312
Proceeds from sale or redemption of marketable securities		54,363	5,180
Purchases of marketable securities		0	(331)
Other investments		3,014	(2,987)
Origination of debt and preferred equity investments		(854,577)	(227,196)
Repayments or redemption of debt and preferred equity investments		663,140	418,371
Net cash (used in) provided by investing activities		(263,773)	2,126,747
Financing Activities
Proceeds from mortgages and other loans payable		779,642	250,514
Repayments of mortgages and other loans payable		(693,243)	(1,663,616)
Proceeds from revolving credit facility and senior unsecured notes		1,072,800	700,000
Repayments of revolving credit facility and senior unsecured notes		(875,697)	(1,664,296)
Proceeds from stock options exercised and DRIP issuance		11,706	4,431
Repurchase of common stock		(211,599)	0
Redemption of preferred stock		(125)	(2,849)
Distributions to noncontrolling interests in other partnerships		(609)	(9,866)
Contributions from noncontrolling interests in other partnerships		33,009	1,434
Dividends/Distributions paid on common and preferred stock/units		(175,790)	(162,243)
Other obligations related to loan participations		10,000	76,500
Deferred loan costs and capitalized lease obligation		(8,521)	(9,307)
Net cash used in financing activities		(58,427)	(2,479,298)
Net (decrease) increase in cash and cash equivalents		(8,478)	20,827
Cash and cash equivalents at beginning of year		279,443	255,399
Cash and cash equivalents at end of period		270,965	276,226
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Issuance of units in the Operating Partnership		20,824	51,647
Redemption of units in the Operating Partnership for stock		13,242	11,795
Derivative instruments at fair value		6,766	7,701
Exchange of debt investment for equity in joint venture		0	68,581
Issuance of preferred units relating to a real estate acquisition		0	22,793
Tenant improvements and capital expenditures payable		7,210	11,637
Fair value adjustment to noncontrolling interest in Operating Partnership		12,712	906
Deconsolidation of subsidiaries		328,644	0
Transfer of assets related to assets held for sale		173,918	1,931,217
Transfer of liabilities related to assets held for sale		149	1,612,008
Deferred leasing payable		800	1,222
Transfer of assets related to assets held for sale		5,754	13,471
Share repurchase payable		41,598	0
Bond repurchase payable		65,416	0
Proceeds from sale held in restricted cash		$ 38,166	$ 0

[1] Included in Other non-cash adjustments is $172.4 million for the six months ended June 30, 2016 for the amortization of the below-market lease at 388-390 Greenwich Street as a result of the tenant exercising their option to purchase the property and entering into an agreement to accelerate the sale.